The structure of lithiophorite, (Al, Li)MnO2(OH)2

Lithiophorite crystallizes in the monoclinic system, space group C2/m, with the constants a= 5-06, b= 2.91, c= 9.55 A, fl= 100 30'. The unit cell contains 2(A1, Li)MnO2(OH)2. The mineral has a layer ;structure in which alternate sheets of MnO6 and (A1, Li)(OH)6 octahcdra are stacked so that the O and (OH) ions of adjacent layers are placed one on top of the other, and held together by hydroxyl bonds. Each layer consists of an infinite two-dimensional sheet formed by octahedra sharing six edges with adjacent ones. The lithium and alumininm occupy similar sites in a layer which can be regarded as a modification of the grouping found in hydrargillite (= gibbsite).